title: A randomized study comparing combined pneumococcal conjugate and polysaccharide vaccination schedules in adults.
abstract: BACKGROUND
  The widely used 23-valent plain polysaccharide vaccine (23vP) has limited effectiveness, produces short-lived immune responses, and induces attenuated antibody production after subsequent challenge with pneumococcal vaccines. Our goal was to examine whether priming with the 7-valent pneumococcal conjugate vaccine (PCV7) could enhance the immunogenicity of 23vP for the PCV7 serotypes and to investigate whether 23vP induced hyporesponsiveness could be overcome using PCV7.
  
  
  METHODS
  We conducted an open-label randomized study that compared 3 vaccine schedules, each of which consisted of 2 doses of PCV7 and 1 dose of 23vP (23vP-PCV7-PCV7, PCV7-23vP-PCV7, PCV7-PCV7-23vP) administered over a 1-year period in a cohort of 348 adults 50-70 years of age. All vaccines were administered intramuscularly and were given 6 months apart. Blood samples were obtained prior to and 1 month after each vaccination.
  
  
  RESULTS
  23vP administered after priming with 2 doses of PCV7 produced significantly higher antibody concentrations for 3 of the 7 PCV7 serotypes, compared with vaccination with a single dose of 23vP; however, the same immunogenicity could be achieved with a single dose of PCV7. Prior vaccination with 23vP attenuated the antibody response to subsequent PCV7, which was not restored by additional doses of PCV7.
  
  
  CONCLUSIONS
  In adults, vaccination schedules combining PCV7 and 23vP do not provide improved immunogenicity over the use of a single dose of 23vP for most of the serotypes contained in PCV7.
authors.affiliation: Oxford Vaccine Group, University of Oxford, Oxford, UK. rajeka.lazarus@doctors.net.uk
authors.forename: Rajeka
authors.initials: R
authors.lastname: Lazarus
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Clutterbuck
authors.forename: Ly-Mee
authors.initials: LM
authors.lastname: Yu
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Bowman
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Bateman
authors.forename: Linda
authors.initials: L
authors.lastname: Diggle
authors.forename: Brian
authors.initials: B
authors.lastname: Angus
authors.forename: Tim E
authors.initials: TE
authors.lastname: Peto
authors.forename: Peter C
authors.initials: PC
authors.lastname: Beverley
authors.forename: David
authors.initials: D
authors.lastname: Mant
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pollard
mesh_terms: D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary / Q000379:methods*; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D014611:Vaccination / Q000379:methods*
chemical_list: C414006:23-valent pneumococcal capsular polysaccharide vaccine; D000907:Antibodies, Bacterial; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines